How did Herbert Spencer define the purpose of philosophy?

Herbert Spencer defined philosophy as a synthesis of the fundamental principles derived from the special sciences. He envisioned this synthesis as a scientific summa intended to replace the theological systems of the Middle Ages.1

Central to his philosophical purpose was the concept of unification through development. Influenced by the evolution of biological species, Spencer sought to apply a universal law of development—which he termed the "law of the multiplication of effects"—to all phenomena, whether cosmic or biological. He argued that because any external force acting upon a homogeneous entity must cause variety to arise, all development is characterized by an increasing complexity and diversity.1

Ultimately, Spencer believed that his philosophical system formed a coherent, ordered structure that supported and enhanced individualism and progress, prioritizing science over religion.23